X-ray and neutron scattering: from ideal zeolites to real guest-host systems

Tetrahedral MOFs, microporous metallophosphates and zeolites share common framework topologies despite very different chemical nature of their crystalline skeleton. In the case of zeolites or metallophosphates, the polymeric [TO2]_ framework is based on single tetrahedral atoms T (T= Si4+/Al3+ or Ga3+/B3+/P5+ respectively) connected by corner oxygen atoms O. In the case of MOFs, the skeleton is built from supertetraedra formed by a central metal atom complexed by 4 organic linkers (terephtalate,...); hence homologous structures expanded by a "scale factor". In "molecular sieves", the static porosity but also the "breathing effect" control, in first approximation, the adsorption and the self-diffusion of guest molecules. These latter are finely tuned by the interaction of these molecules with the framework itself (though H-bonds or electrostatic interactions), with charge compensating cations in basic zeolites (through coulombic interaction), or with other adsorbed molecules. However, the interplay between guest molecule adsorption, framework relaxation, cation redistribution and atomic charge transfer leads to an inextricable problem for the modeling and prediction of adsorption properties in these systems in absence of any polarizable and adaptive force field. We will present experimental charge density studies on activated industrial zeolites FAU, MFI and MOR. The electrostatic properties derived on these systems (electric field, atomics charges) are validated by a comparison with those derived, experimentally and theoretically, on a comprehensive set of simpler quartz-type materials (SiO2, AlPO4, GaPO4,...) representative of typical microporous compositions. Finally, we will combine the informations brought by diffraction, diffuse scattering and Monte-Carlo modelling to analyse the adsorption process or the role of the template in the stabilisation of the framework in these systems and in the famous MIL-53 MOF

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Molecular Dynamics Simulation Studies of p-Xylene in OH-free Si-MCM-41

Zeitschrift für Naturforschung A ◽

10.1515/zna-2005-11-1207 ◽

2005 ◽

Vol 60 (11-12) ◽

pp. 805-813 ◽

Cited By ~ 5

Author(s):

Tanin Nanok ◽

Philippe A. Bopp ◽

Jumras Limtrakul

Keyword(s):

Molecular Dynamics ◽

Electrostatic Interactions ◽

Zeolite Catalysts ◽

Van Der Waals Interactions ◽

Dynamics Simulation ◽

Guest Molecules ◽

Self Diffusion ◽

Order Of Magnitude ◽

Average Potential Energy ◽

Mcm 41

We report on modeling efforts and molecular dynamics computer simulations of the structure and self-diffusion of p-xylene in OH-free Si-MCM-41 as a function of loading. Both the guest molecules and Si-MCM-41 are modeled as flexible entities. With this newly developped intermolecular force field the average potential energy of p-xylene in the pore increases with increasing loading. The adsorption of p-xylene in MCM-41 is primarily associated with the van der Waals interactions of the model, whereas the contribution from electrostatic interactions is relatively small (about 2 kcal/mol), in accordance with other aromatic hydrocarbons adsorbed in zeolite catalysts. The calculated selfdiffusion coefficients of p-xylene in Si-MCM-41 are well comparable with diffusion coefficients of pyridine in MCM-41 and of the same order of magnitude as in liquid p-xylene. Increasing the loading results in non-negligible mutual p-xylene interaction, thus leading to a decrease of the self-diffusion coefficient.

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Thermal and Transport Properties of Molten Chloride Salts with Polarization Effect on Microstructure

Energies ◽

10.3390/en14030746 ◽

2021 ◽

Vol 14 (3) ◽

pp. 746

Author(s):

Jianfeng Lu ◽

Senfeng Yang ◽

Gechuanqi Pan ◽

Jing Ding ◽

Shule Liu ◽

...

Keyword(s):

Heat Capacity ◽

Polarization Effect ◽

Chloride Salt ◽

Coulombic Interaction ◽

Molten Chloride ◽

Self Diffusion ◽

Local Structures ◽

Property Data ◽

Chloride Salts ◽

And Storage

Molten chloride salt is recognized as a promising heat transfer and storage medium in concentrating solar power in recent years, but there is a serious lack for thermal property data of molten chloride salts. In this work, local structures and thermal properties for molten chloride salt—including NaCl, MgCl2, and ZnCl2—were precisely simulated by Born–Mayer–Huggins (BMH) potential in a rigid ion model (RIM) and a polarizable ion model (PIM). Compared with experimental data, distances between cations, densities, and heat capacities of molten chloride slats calculated from PIM agree remarkably better than those from RIM. The polarization effect brings an extra contribution to screen large repulsive Coulombic interaction of cation–cation, and then it makes shorter distance between cations, larger density and lower heat capacity. For NaCl, MgCl2, and ZnCl2, PIM simulation deviations of distances between cations are respectively 3.8%, 3.7%, and 0.3%. The deviations of density and heat capacity for NaCl between PIM simulation and experiments are only 0.6% and 2.2%, and those for MgCl2 and ZnCl2 are 0.7–10.7%. As the temperature rises, the distance between cations increases and the structure turns into loose state, so the density and thermal conductivity decrease, while the ionic self-diffusion coefficient increases, which also agree well with the experimental results.

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Antimicrobial, Antifertility and Antiinflammatory Approach to Tetradentate Macrocyclic Complexes of Iron(II) and Manganese(II)

Metal-Based Drugs ◽

10.1155/mbd.2002.347 ◽

2002 ◽

Vol 8 (6) ◽

pp. 347-353 ◽

Cited By ~ 9

Author(s):

Ashu Chaudhary ◽

D. P. Jaroli ◽

R. V. Singh

Keyword(s):

Molecular Weight ◽

Reproductive Organs ◽

Spectral Studies ◽

Central Metal Atom ◽

Central Metal ◽

Testicular Sperm ◽

Mass Spectral ◽

Sperm Density ◽

Elemental Analyses

Some antifertility inhibitors of 18 to 24-membered tetraazamacrocyclic complexes of iron(II) and manganese(II) have been synthesised by the template condensation using 1,3-phenylenediamine with malonic acid, succinic acid, glutaric acid and adipic acid. The reaction proceed smoothly to completion. The complexes were characterized by elemental analyses, molecular weight determinations, infrared, electronic, magnetic moment, mössbaur and mass spectral studies. The elemental analyses are consistent with the formation of the complexes [M(N4Ln)Cl2] (M = Fe(lI) or Mn(II)). All these complexes are stable and monomeric in nature as indicated by the molecular weight determinations. The spectral studies confirm the octahedral geometry around the central metal atom. The complexes have been screened in vitro against a number of fungi and bacteria to assess their growth inhibiting potential. The testicular sperm density and testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trials and biochemical parameters of reproductive organs have been examined and discussed.

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Calix[4]arene-Based MOFs Controlled by Length of Alkyldiammonium Guests

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314082862 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1713-C1713

Author(s):

Ki-Min Park ◽

Eunji Lee ◽

Huiyeong Ju ◽

Suk-Hee Moon ◽

Shim Sung Lee

Keyword(s):

Electrostatic Interactions ◽

Three Dimensional ◽

Van Der Waals Interactions ◽

Supramolecular Interactions ◽

Solvothermal Reaction ◽

Guest Molecules ◽

Structural Framework ◽

Guest Species ◽

Dimensional Network ◽

Alternative Conformation

Our interest in the development of MOFs with the cavities controlled by guest species has led us to investigate the MOFs based on calix[4]arene derivatives, in which metal ions link the calix unit to give the networks with the cavities accommodating several guest species, because the calix[4]arene-based MOFs contain porosity associated with both the ligand itself and the structural framework. In the present work, we employed a low rim-functionalized calix[4]arene tetraacetic acid (H4CTA) with 1,3-alternative conformation as a multidentate building block and alkyldiamines as the guest molecules. In the solvothermal reaction of H4CTA and Zn(II) ion in the presence of alkyldiamines, two types of new MOFs based on calix[4]arene tetraacetate (CTA4-) depending on the lengths of α,ω–alkyldiammonium guests have been synthesized by including suitable alkyldiammonium guests. Their single-crystal X-ray diffraction analyses reveal that the short alkyldiammonium guests such as ethyldiammonium, propyldiammonium, and butyldiammonium lead to form two-dimensional framework with the cavity consisting of two CTA4-and four Zn(II) ions whereas the alkyldiammonium guests such as heptyldiammonium, octyldiammonium, nonyldiammonium, and decyldiammonium give rise to generate three-dimensional network with the cavity surrounded by six CTA4-and four Zn(II) ions. The alkyldiammonium guests in both MOFs are well accommodated by each cavity via a variety of supramolecular interactions including electrostatic interactions, hydrogen bonds and van der Waals interactions. We will present and discuss a study on the syntheses and characterization of two new MOFs based on calix[4]arene derivative.

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Synthesis, Crystal Structure and Antimicrobial Activity of Poly [bis-and#181;-3,5-dinitro-2-oxidobenzoato) (py) Cu II]

Journal of the chemical society of pakistan ◽

10.52568/000693 ◽

2020 ◽

Vol 42 (6) ◽

pp. 928-928

Author(s):

Fouzia Chang Fouzia Chang ◽

Najma Memon Najma Memon ◽

Shahabuddin Memon Shahabuddin Memon ◽

Muhammad Naeem Ahmed Muhammad Naeem Ahmed ◽

Muhammad Nawaz Tahir Muhammad Nawaz Tahir ◽

...

Keyword(s):

Molecular Structure ◽

Single Crystal ◽

Room Temperature ◽

Central Metal Atom ◽

Central Metal ◽

Single Crystal Xrd ◽

Monoclinic System ◽

X Ray ◽

Pyramidal Geometry ◽

Square Pyramidal Geometry

A novel Poly [bis-and#181;-3,5-dinitro-2-oxidobenzoato) (py) Cu II]/(C12H7CuN3O7) was synthesized by a self assemble method at room temperature. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P 2 1/c with lattice parameters of a = 10.2143, b = 5.1651 and c = 26.608, α = 90, β = 99.720, γ = 90, Z = 4, V = 1383.60 (18) and#197;3.Pore size depicted from single crystal XRD data was 47and#197;. The central metal atom Cu (II) is coordinated with oxygen of carboxylates group and nitrogen atom of pyridine. The coordination polyhedron posses square pyramidal geometry is manifested by the N— Cu—O angle of 90o. The structure is composed of monomeric coordination units with the central copper (II) ion is not occupying a centre of symmetry.

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Synthesis and Properties of a New Kind of One-Dimensional Conductors. 1. General Aspects

Zeitschrift für Naturforschung A ◽

10.1515/zna-1979-0810 ◽

1979 ◽

Vol 34 (8) ◽

pp. 983-985 ◽

Cited By ~ 18

Author(s):

Michael Hanack ◽

Friedrich Franz Seelig ◽

Joachim Strähle

Keyword(s):

Experimental Studies ◽

Bidentate Ligand ◽

Central Metal Atom ◽

Central Metal ◽

Bridging Ligands ◽

One Dimensional ◽

Bridging Ligand ◽

Linear Chains ◽

Square Planar ◽

General Aspects

AbstractA model for a new kind of one-dimensional conductors is presented. The compounds consist of square-planar metal complexes MX4 which are polymerised via bridging ligands L to linear chains. The bidentate ligand L, e.g. C22-, leads to the formation of a linear π-system along the chain, which is essential for the conductivity. The square-planar complex can be, for example, a metal phthalocyanine. MO-calculations show that this kind of polymer gives rise to a suitable energy band structure. An advantage of the new one-dimensional conductors is their flexibility; different combinations of the square-planar ligand system, the bridging ligand, and the central metal atom can be used. First experimental studies show that the preparation of the proposed conductors is possible.

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Contribution of electrostatic interactions to the concentration dependence of the self-diffusion coefficient of brownian particles

Chemical Physics Letters ◽

10.1016/0009-2614(83)80663-0 ◽

1983 ◽

Vol 102 (1) ◽

pp. 83-87 ◽

Cited By ~ 4

Author(s):

Nobuo Yoshida

Keyword(s):

Diffusion Coefficient ◽

Concentration Dependence ◽

Electrostatic Interactions ◽

The Self ◽

Self Diffusion ◽

Brownian Particles ◽

Self Diffusion Coefficient

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Microwave Molecular Sieves Synthesis and Capillary Crystal Growth by Geometric Confinement.

MRS Proceedings ◽

10.1557/proc-782-a5.13 ◽

2003 ◽

Vol 782 ◽

Author(s):

Steven B. Ogunwumi ◽

John F. Wight ◽

James C. Fajardo

Keyword(s):

Molecular Sieves ◽

Molecular Sieve ◽

Crystal Size ◽

Mesoporous Molecular Sieve ◽

Guest Molecules ◽

Microwave Hydrothermal ◽

Geometric Confinement ◽

Capillary Bundle ◽

And Control ◽

Mcm 41

ABSTRACTMicrowave heating is an alternate means for material processing. The technique is promising for the accelerated synthesis of new materials. Microwave molecular sieves synthesis is combined with capillary confinement as a novel synthetic method. It is successfully demonstrated in the preparation of small ZSM-5 crystals by microwave hydrothermal synthesis within 1–1.7 μm channels of a capillary bundle. The geometric and spatial confinement offered by the capillary is expected to define and control the resulting crystal size distribution and orientation.MCM-41, a mesoporous molecular sieve with a uni-dimensional regular array of hexagonal channels is investigated as a candidate for capillary confinement. The large porous channels of MCM-41(>35 å ) is attractive as a host for promoting inclusions of guest molecules or templates. The successful confinement of MCM-41 represents an important step towards the alignment of molecular sieves in a defined orientation within thin capillaries bundled (less than 5 μm channels). Ultimately, such an approach may be useful for the fabrication of new molecular sieve devices.

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Investigation of a New Xanthate Ligand. The Crystal and Molecular Structures of Nickel and Cadmium (Methoxyethyl)xanthates

Australian Journal of Chemistry ◽

10.1071/ch9881117 ◽

1988 ◽

Vol 41 (7) ◽

pp. 1117 ◽

Cited By ~ 11

Author(s):

BF Abrahams ◽

BF Hoskins ◽

ERT Tiekink ◽

G Winter

Keyword(s):

Crystal Structures ◽

Metal Atom ◽

Molecular Structures ◽

Central Metal Atom ◽

Central Metal ◽

Crystal And Molecular Structures ◽

Cadmium Compound

The crystal structures of Ni(S2COCH2CH2OCH3)2 and Cd (S2COCH2CH2OCH3)2 have been determined. Crystals Ni(S2COCH2CH2OCH3)2 are orthorhombic, Pbca , with a 7.852(1), b 7.126(2), c 24.963(4)Ǻ, Z 4. Crystals of Cd (S2COCH2CH2OCH3)2 are monoclinic, P21/c, with a 12.712(2), b 4.215(1), c 13.400(2)Ǻ, β 104.60(1)°, Z 2. In both structures the central metal atom is coordinated by the sulfur atoms in a planar arrangement, an unexpected observation for the cadmium compound.

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